Feeder wire structure for high pressure fuel injection unit

ABSTRACT

An accumulator type of fuel injection nozzle having an injection valve that is controlled by an electromagnet within the accumulator chamber includes a feeder wire structure formed axially in the outer housing assembly of the injection nozzle for energizing the electromagnet. This feeder wire structure includes one or more axially extending wire passages formed in the outer housing assembly, preferably in a structure through which is formed a fuel inlet conduit, constructed so as to withstand the high pressure within the accumulator chamber, to provide a sufficient seal without increasing the outer diameter of the injection nozzle, and to provide easy installation of the injection nozzle without interference from the engine. One or more feeder wires are contained within the wire passages for energizing the electromagnet.

BACKGROUND OF THE INVENTION

This invention relates to a high pressure fuel injection unit for anengine, and more particularly to an improved feeder wire structure forenergizing an electromagnetic assembly of the injection unit.

One popular form of fuel injection unit for engines is the so-called"accumulator type." This type of injection nozzle includes anaccumulator chamber that is charged with fuel under pressure and whichcommunicates with a nozzle port. An injection valve is supported withinthe accumulator chamber and controls the discharge through the nozzleport. An actuating device is associated with the injection valve and ismovable within a control chamber that is also pressurized with fuel. Avalve is associated with the control chamber and is opened so as toreduce the pressure and cause the pressure in the accumulator chamber tounseat the injection valve and initiate fuel injection. Typically, thevalve is operated by a main electromagnetic assembly that is containedwithin the housing of the fuel injection nozzle.

To control the amount of fuel injected, the inventors have proposed toprovide an additional and separate sub-electromagnetic assembly withinthe accumulator chamber to control the lift movement of the injectionvalve. It has also been proposed to provide a wire passage which extendsradially through the side wall of the accumulator chamber in which awire harness is supported for operating this sub-electromagneticassembly. Although this type of feeder wire structure is generallysatisfactory, the angular orientation of the wire passage in relation tothe housing can give rise to sealing, size and installation problems.For example, when the wire passage extends perpendicularly or at anangle to the housing axis, the side wall of the accumulator chamber isusually not thick enough to provide a sufficient seal around the wiringpassage so as to withstand the high pressure within the accumulatorchamber. This typically has required that the diameter of the fuelinjection unit be enlarged to improve the effectiveness of the seal. Inaddition, when the wire passage is disposed at an angular relationshipto housing axis, the wires may interfere with the engine or othercomponents which can make installation of the injection unit in theengine difficult.

It is, therefore, a principal object of this invention to provide animproved feeder wire structure for an electromagnetic assembly withinthe accumulator chamber of this type of fuel injection unit.

It is a further object of this invention to provide an improved feederwire and sealing structure for this type of fuel injection unit which iscapable of withstanding the high pressure in the accumulator chamber.

It is yet another object of this invention to provide an improved feederwire and sealing structure for an accumulator type fuel injection unitwhich provides a sufficient seal without the need for increasing theouter diameter of the injection unit.

It is still another object of this invention to provide an improvedfeeder wire structure which does not present a problem with respect toinstallation of the injection unit in the engine.

SUMMARY OF THE INVENTION

This invention is adapted to be embodied in an accumulator type ofinjection nozzle that is comprised of an outer housing assembly defininga cavity partitioned into an accumulator chamber which is adapted to besupplied with high pressure fuel and a coil chamber. A nozzle port leadsfrom the accumulator chamber and an injection valve is moveable betweena closed position and an open position for controlling the discharge offuel from the accumulator chamber through the nozzle port. A controlchamber is also incorporated that receives pressurized fuel. Anactuating member is supported for movement within this control chamberand is associated with the injection valve for retaining the injectionvalve in its closed position when the control chamber is pressurized andfor movement of the injection valve to its open position when pressureis relieved in the control chamber. A valve means is moveable between aclosed position for maintaining pressure in the control chamber and anopen position for relieving pressure in the control chamber foreffecting fuel discharge through the nozzle port.

In accordance with the invention, a first electromagnet is positionedwithin the accumulator chamber for controlling the injection valve. Atleast one wire passage is formed in the outer housing assembly andextends axially and has at least one feeder wire extending axiallytherethrough for energizing the first electromagnet.

In accordance with one embodiment of the invention, a secondelectromagnet is provided within the coil chamber for moving the valvemeans to one of the positions when this second electromagnet isenergized, and the first electromagnet controls the lift of theinjection valve so as to vary the amount of fuel which is dischargedfrom the nozzle port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional front view of a fuel injection nozzleconstructed in accordance with an embodiment of the invention.

FIG. 2 is a cross-sectional side view of the fuel injection nozzle.

FIG. 3 is an enlarged cross-sectional view of the control chamberportion of the fuel injection nozzle.

FIG. 4(a) is a bottom view of the shim plate of the fuel injectionnozzle.

FIG. 4(b) is a cross-sectional view taken along line IV(b)-IV(b) of FIG.4(a).

FIG. 5 is a bottom view of the cover member of the fuel injectionnozzle.

FIG. 6(a) is a top plan view of the partitioning plate of the fuelinjection nozzle.

FIG. 6(b) is a bottom view of the partitioning plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION

Referring to the drawings, and in particular to FIGS. 1 and 2, a fuelinjection nozzle constructed in accordance with an embodiment of theinvention is identified generally by the reference numeral 11. Theinjection nozzle 11 is comprised of an outer housing assembly, indicatedgenerally by the reference numeral 12, that is adapted to be mounted, ina manner to be described, in the cylinder head of an internal combustionengine with a nozzle port 13 communicating with the combustion chamberfor delivering fuel to it in a manner to be described. The invention maybe used for direct cylinder injection, or instead may be utilized inconjunction with manifold injection systems. The invention, however, hasparticular utility with direct fuel injection, for example, as used withhigh speed diesel engines.

Fuel is supplied to the injection nozzle 11 from a remotely positionedfuel tank (not shown) by means of a high pressure pump (not shown).Excess fuel is returned back to the fuel tank or reservoir through areturn line.

The outer housing assembly 12 is comprised of a casing body 14 and acover member 15 which is removably seated within an opening 16 at thetop of the casing body 14. The casing body 14 has a threaded lower end17 which is adapted to be threaded into a suitable aperture in thecylinder head of the associated engine (not shown) in a known manner.The nozzle port 13 is defined by a tip 18 that has a threaded portionwhich is received in a threaded bore 19 formed at the lower end of thecasing body 14. An adjusting shim 21 is interposed between the nozzlepiece 18 and the lower end of the casing body 14 for length adjustmentof the fuel injection nozzle 11.

An injection valve 22 is slidably supported within a bore 23 of thenozzle piece 18 and has a guide portion 24 formed with a helical grooveat its lower portion, and a flow controlling tip 25 which, when in theclosed position, closes the injection nozzle port 13.

An accumulator chamber 26 is formed at the upper end of and above thebore 23 in the lower portion of the casing piece 14. The accumulatorchamber 26 is closed at its upper end by means of a partitioning plate27 that is held against a shoulder 28 in the casing body 14 by abottomed cylindrical pipe portion 29 of the cover member 15. A cap 31having a threaded bore engages a threaded portion of the upper portionof the casing body 14 and presses against a top plate 32 of the covermember 15 to hold it in position.

The cover member 15 is formed with an inlet conduit 33 that has athreaded external portion 34 so as to receive a fitting 35 forconnecting a supply line 36 extending from the pressure pump to theinlet conduit 33. The inlet conduit 33, which is generally a drilledopening, extends axially along the cover member 15 at its periphery atone side thereof and communicates at its lower end with the accumulatorchamber 26 through a corresponding fuel groove 37 formed in thepartitioning plate 27 and groove 39 in spacer 40 for delivering fuel tothe accumulator chamber 26.

The partitioning plate 27 is generally disc-shaped, as shown in FIG.6(a) and (b), and serves to separate the accumulator chamber 26 from acoil chamber 38 in the upper portion of the casing body 14. Thepartitioning plate 27 has a centrally positioned aperture 41 into whichan actuator portion 42 of the injector valve 22 is slidably supportedand which closes a control chamber 43 formed within the partitioningplate 27 in a space defined by the upper portion of this aperture 41 andan inner face 44 of the partitioning plate 27, as shown in FIG. 3. Ashim plate 45 is positioned between a top face 46 of the actuatorportion 42 and the partitioning plate face 44 as shown in FIG. 3 foradjusting the lift of the injection valve 22.

The shim plate 45 is an annular plate, as shown in FIGS. 4(a) and 4(b),and has raised portions 47 projected every 90 degrees which abut againstthe partitioning plate face 44. Grooved portions 48 are interposed inbetween for receiving pressurized fluid. This shim plate 45 may beinstalled upside down.

A restricted orifice 49 communicates the control chamber 43 with thecoil member 38. As shown in FIG. 3, a throttle hole 51 fixed in the endof the actuator portion 42 and an axial passage 52 formed through theupper portion of the injection valve 22 communicate the control chamber43 with the accumulator chamber 26. The control chamber 43 communicateswith the throttle hole 51 to receive the pressurized fluid and normallyurge the injection valve 22 toward its downward or closed position.

A coil compression spring 53 encircles the injection valve 22, and atits lower end engages a cup-shaped retainer 54 that is held axially inposition against the helical groove of the guide portion 24. The upperend of the spring 53 bears against an upper spring seat 55 which ispositioned against a shoulder formed by an enlarged portion 56 at thelower end of a bore 57 formed in a holder member 58. The coilcompression spring 53 acts to further assist in maintaining theinjection valve 22 in the closed position, as shown in FIGS. 1 and 2.

A valve 59 is supported at the upper end of the partitioning plate 27and controls the opening of the restricted orifice 49. The valve 59comprises a headed portion 61 that is received within a correspondingrecess formed in an enlarged disc-like armature plate 62, and a stemportion 63 which is in engagement with a spring 64 so as to bias thevalve 69 toward its closed position to maintain the orifice 49 in itsclosed position.

The valve 59 is opened and closed so as to control the discharge of fuelfrom the nozzle port 13 by means of an electromagnetic assembly,indicated generally by the reference numeral 65. This electromagneticassembly 65 includes a generally cylindrical yoke 66 that has a threadedopening at an enlarged diameter lower end portion which is received on athreaded portion of the partitioning plate 27 so as to secure theelectromagnetic assembly 65 in position. The electromagnetic assembly 65is further comprised of a solenoid coil or winding 67 that is disposedwithin the housing or yoke 66 and which encircles an armature 68. Thearmature 68 is formed with a bore that slidably supports the valve stem63 of the valve 59.

A circuit (not shown) is used for energizing the coil 67 of theelectromagnetic assembly 65 for opening and closing the valve 59.

The condition shown in FIGS. 1 and 2 is that which occurs when thewinding 67 is de-energized. When the winding 67 is de-energized, thevalve 59 will be held in its closed position by the spring 64 so thatthe accumulator chamber 26 and control chamber 43 may be pressurized.

At the appropriate instant for fuel injection to begin, which may becontrolled by any suitable strategy, the winding 67 is energized. Whenthis happens, the valve armature 62 will be attracted upwardly by theflux in the armature 68 so as to urge the stem portion 63 upwardly andopen the valve 59 against the action of the spring 64. This will openthe orifice 49 to rapidly deplete the pressure in the control chamber43. The higher pressure of the fuel acting in the accumulator chamber 26will then urge the injection valve 22 upwardly to its open position andpermit fuel to issue from the nozzle port 13. When the fuel pressure inthe accumulator 26 has been depleted, the spring 64 will move theinjection valve 22 to its closed position and the fuel pressure can thenbuild up in the accumulator chamber 26. This action is initiated bydiscontinuing the energization of the winding 67 so as to close thevalve 59 and permit pressure in the control chamber 43 to again buildup.

The amount of fuel injected can be varied by varying the lift distanceof the injection valve 22 by energizing or de-energizing a coil 72 of asub-electromagnetic assembly, indicated generally by the referencenumeral 71, and which is positioned within the accumulator chamber 26for adjusting the lift and/or for detecting the lift of the injectionvalve 22. The coil 72 is supported within the holder member 58. Aregulating member 73 comprised of an armature 74 fixed on the upper endof a cylindrical guide portion 75 which is slidably supported within thebore 57 of the holder member 58 regulates the lift amount of theinjection valve 22. The lower end of the cylindrical guide portion 75 ispositioned above a stopper portion 76 of the injection valve 22 todefine a smaller lift distance of the injection valve 22. A stopperplate 78 made of non-magnetic material is positioned above the armature74 and in contact with the lower end of the partitioning plate 27 so asto provide a stop surface for the regulating member 73 and to preventtransmission of stray magnetic flux paths through the partitioning plate27.

If injection of a larger amount of fuel is desired, the coil 72 ismaintained in a de-energized state so as to allow the regulating member73 to move freely between the top surface of the holder member 58 andthe stopper plate 78. In this condition, the injection valve 22 will beurged upward the distance defined by the space between the top face ofthe shim plate 45 and the partitioning plate face 44. On the other hand,if injection of a smaller amount of fuel is desired, the coil 72 isenergized. When this occurs, the armature 74 is attracted downwardly bythe flux in holder member 58 so as to lower the cylindrical guideportion 75. In this state, the injection valve 22 will be moved upwardthe distance defined by the space between the lower end face of theguide portion 75 and the upper face of the injection valve stopperportion 76 so as to permit a smaller amount of fuel to issue from thenozzle port 13.

With this type of arrangement, the amount of fuel delivered to thecombustion chamber during each cycle of operation can be controlled aswell as the injection pattern so as to provide optimum fuel delivery andcontrol.

In accordance with the invention, a feeder wire structure is providedfor energizing the coil 72 of the sub-electromagnetic assembly 71 so asto vary the lift distance of the injection valve 22 so that a larger orsmaller amount of fuel can be injected, as desired. This structureincludes a pair of bores 81 which extend axially through the cap 31 andcover member 15 in the periphery thereof to provide a wire passage forfeeder wires to the coil 72. The feeder wires are defined by a pair ofterminal feeder rods 82, preferably made of copper, which extend throughthe bores 81 with insulating sleeves 83 being interposed between holdingportions 84 of the bores 81 and larger diameter portions 85 of thefeeder rods 82. The larger diameter portions 85 of the feeder rods 82are fixed to the inner surface of the insulating sleeves 83 with a highstrength adhesive to withstand the high fuel pressure within theinjection nozzle 11. A soft sealing adhesive 87 is interposed between asmaller diameter portion 88 of each feeder rod 82 and a sealing portion89 of the bores 81. This sealing adhesive 87 is longitudinallycompressed by the fuel pressure within the accumulator chamber 26 whichacts on the lower end of the adhesive 87 causing it to radially expandso as to provide a strong seal around the smaller diameter portion 88 ofeach feeder rod 82 within the coil chamber 38. A nut 86 is affixed onthe posts 90 of each rod 82 so as to afford attachment to an appropriatelead wire (not shown).

The lower ends of the smaller diameter portions 88 extend throughcircumferential grooves 91 in the partitioning plate 27 and arepositioned in proximity to guide holes 92 in the spacer 40. A pair ofwire harnesses 94 are connected to the coil 72 and extend downwardlythrough guide holes 95, and then upwardly through guide grooves 96 and97, where the wires 94 are soldered to the lower ends of the smallerdiameter portions 88.

With this type of feeder wire structure wherein the bores or wirepassages 81 extend axially through the outer housing assembly 12, thewire passages 81 can be sealed along their entire length to insure asufficient seal against the high pressure which forms within the fuelinjection nozzle 11, without the need for increasing the outer diameterof the injection nozzle 11. The seal is particularly effective when thewire passages 81 is formed in the cover member 15 or like structurewhich is originally formed thicker to accommodate the inlet conduit 33.This construction also eliminates the need for increasing the outerdiameter of the injection nozzle 11. It should be noted that, althoughthe wire passages 81 are formed through the cover member 15 in thepreferred embodiment, these wire passages 81 may instead be formedthrough another structure in which the inlet conduit 33 is formed, forexample, through the casing body 14 when the inlet conduit 33 is formedtherein.

This type of feeder wire structure also provides for easy installationof the injection nozzle 11 into the engine and permits the injectionnozzle 11 to be oriented in any number of different positions within theengine without interference from the engine or other components.

Moreover, the cylindrical pipe portion 29 of the cover member 15 has apair of knock pin holes 101 formed in the lower portion. Knock pins 102are fitted into these pin holes 101 and extend downwardly through knockpin grooves 103, 104 and 105 formed through the periphery of thepartitioning plate 27, the spacer 40 and the holder member 58respectively, and are fitted into oppositely oriented knock pin holes106 formed in the shoulder 28. These knock pins 102 serve to preventthese components from rotating relative to each other, and thus toprevent the feeder wire structure from becoming displaced.

Although the feeder wire structure has been described in connection withan electromagnetic assembly 71 for regulating the lift amount of theinjection nozzle 22, it should be noted that this feeder wire structureis not so limited, and instead may also be used with other types ofelectromagnetic assemblies positioned in a chamber which is subjected tohigh pressures.

It is to be understood that the foregoing description is only that of apreferred embodiment of the invention, and that various changes andmodifications may be made without departing from the spirit and scope ofthe invention, as defined by the appended claims.

We claim:
 1. An accumulator type of injection nozzle comprising an outerhousing assembly defining a cavity partitioned into an accumulatorchamber adapted to be supplied with high pressure fuel and a coilchamber, a nozzle port leading from said accumulator chamber, aninjection valve moveable between a closed position and an open positionfor controlling the discharge of fuel from said accumulator chamberthrough said nozzle port, a control chamber for receiving pressurizedfuel, an actuating member supported for movement within said controlchamber and associated with said injection valve for retaining saidinjection valve in its closed position when said control chamber ispressurized and for movement of said injection valve to its openposition when pressure is relieved in said control chamber, valve meansmoveable between a closed position for maintaining pressure in saidcontrol chamber and an open position for relieving pressure in saidcontrol chamber for effecting fuel discharge through said nozzle port, afirst electromagnet within said accumulator chamber for controlling thelift of said injection valve, and at least one wire passage formed insaid outer housing assembly and extending axially, .[.and.]. at leastone feeder wire extending axially through said wire passage forenergizing said first electromagnet.Iadd., and seal means associatedwith said wire passage for sealing said wire passage so that it is ableto withstand the pressure within said accumulator chamber.Iaddend.. 2.An accumulator type of injection nozzle as recited in claim 1, furthercomprising a second electromagnet within said coil chamber for movingsaid valve means to one of said positions when said second electromagnetis energized.
 3. An accumulator type of injection nozzle as recited inclaim 1, wherein an inlet conduit is formed in said outer housingassembly and extending axially for supplying fuel to said accumulatorchamber.
 4. An accumulator type of injection nozzle as recited in claim3, wherein said wire passage and said inlet conduit are formed in theperiphery of said outer housing assembly.
 5. An accumulator type ofinjection nozzle as recited in claim 1, wherein said outer housingassembly comprises a cover member seated in said cavity, wherein saidwire passage and an inlet conduit for supplying fuel to said accumulatorchamber are formed in said cover member and extending axially.
 6. Anaccumulator type of injection nozzle as recited in claim 5, wherein saidwire passage and said inlet conduit are formed in the periphery of saidcover member. .[.7. An accumulator type of injection nozzle as recitedin claim 1, further comprising seal means associated with said wirepassage for sealing said wire passage so that it is able to withstandthe pressure within said accumulator chamber..].
 8. An accumulator typeof injection nozzle as recited in claim 1, wherein said wire passage isformed in the periphery of said outer housing assembly.
 9. Anaccumulator type of injection nozzle as recited in claim 1, furthercomprising a casing body and a cover member each having a plurality ofholes formed in the periphery thereof, a partitioning plate forpartitioning said cavity into said accumulator chamber and said coilchamber, said partitioning plate having a plurality of grooves formed inthe periphery thereof, said accumulator type of injection nozzle furthercomprising a plurality of pins each of which is fitted into acorresponding casing body and cover member hole and a correspondingpartitioning plate groove for preventing said casing body, said covermember and said partitioning plate from rotating relative to each other.